Whiplash related injuries are caused by the rapid acceleration of a person's cranium and cervical spine, which occurs, for example, in a rear end automobile collision. The rapid acceleration causes the extension and flexion of the cervical spine which, in turn, can cause severe injury. Types of whiplash related injuries include fractured and/or dislocated vertebrae, torn ligaments (both anterior and posterior of the spinal column), and evulsion of parts of the vertebrae, ligaments and intervertebrae discs. Similar injuries can occur to the thoracic and lumbar spinal areas.
It has thus been found, for example, that the C4, C5 and C6 cervical vertebrae, and the paravertebrae ligaments are most often damaged with whiplash related injuries, although the entire cervical as well as the thoracic and lumbar spine may well be involved. Rapid extension of the cervical spine can thus stretch the anterior longitudinal ligament, thus placing it in traction and causing either bone or ligamentous damage. Such hyperextension typically damages the C1 through C7 cervical vertebrae. The vertebral artery, which extends through an opening in the cervical vertebrae, and the sympathetic nerve fibers that surround the artery are also often damaged. These types of injuries cause severe disabilities and, in some instances, death.
Seatbacks and/or head restraints in automobiles, trucks, and other types of vehicles are provided to prevent whiplash related injuries to passengers during collisions, but typically fail. During a rear-end vehicle collision, the forces of the collision typically cause a passengers's cranium and cervical spine to rapidly accelerate toward the rear of the vehicle. Once the cranium strikes the seatback or head restraint, it then rapidly accelerates in the opposite direction toward the front of the vehicle. The rearward acceleration of the cranium, and resulting collision with the seatback or head restraint, causes injury of the cervical spine and, thus typically injuries the anterior structure of the passenger's neck. The forward acceleration of the cranium, on the other hand, causes hyperflexion of the cervical spine and typically the posterior structure of the neck.
In my issued U.S. Pat. Nos. 5,181,763 and 5,290,091, the entire disclosures of which are hereby incorporated by reference, apparatus is disclosed for preventing whiplash-related injuries to a passenger in a vehicle. The characteristic shapes of the devices shown therein define a supporting means and contour located behind the cranium and cervical spine of the passenger that interfit with the posterior contour of the passenger's cranium and cervical spine. The supporting means interacts with the passenger during rear end impact to maintain the pre-collision shape of the supported spinal zones, to thereby aid in the avoidance of whiplash and similar injuries.
It may be noted in the foregoing discussions, that the construction of most prior art seatbacks and head restraints incorporate materials that in an effort to provide maximum comfort, are highly resilient. Such materials while they may absorb some of the impact energy which is generated as the passenger is thrown rearwardly against the seat during a rear end impact, promptly transfer the absorbed energy back to the passenger, causing a rebound effect, which only adds to the detrimental conditions which foster injury.
In accordance with the foregoing, it may be regarded as an object of the present invention, to overcome the problems and disadvantages of known apparatus for preventing whiplash, such as vehicle head restraints and seatbacks.
It is a further object of the present invention, to provide apparatus of the foregoing type, which includes means for efficiently and safely absorbing impact energy, thereby further diminishing the likelihood of passenger injury.
In my further issued U.S. Pat. No. 5,580,124 (the entire disclosure of which is hereby incorporated by reference) there is disclosed a vehicle-installed supporting seat for a passenger, which includes a seat back provided with an integral head-neck restraint comprising a cranium support portion and a cervical spine support portion. Each said portion includes a layer of resilient material supported on an underlying inflexible support shell, which together act to effectively define a contour that interfits with the posterior contour of the passenger's cranium and cervical spine. The support shell is rearwardly displaceable upon being subjected to impressed forces generated from the passenger pressing against the restraint as a result of a rear end impact at said vehicle. A controllably deformable energy absorbing crush zone is disposed to the rear of the shell as to be compressed by the rearward displacement of the shell. The interfitting contour and thereby the inflexible shell, upon being displaced by said forces toward the underlying crush zone, retain the shape of the contour, whereby the cervical and cranium support portions act to substantially simultaneously decelerate the cranium and cervical spine of the passenger during a vehicle rear end impact, while the controlled deformation of the crush zone absorbs energy, to prevent whiplash-related injuries to the passenger.
The apparatus of the U.S. Pat. No. 5,580,124 patent preferably further includes a thoracic and lumbar spine support portion which are defined by downward extension of the support shell, resilient material and contour; whereby the thoracic and lumbar spine portion of the passenger are decelerated with the cranium and cervical spine during a rear end impact.
The thoracic section of the human spine is believed to be compressed and flattened during a rear end impact. In addition to being injured, this flattening of the thoracic spine causes axial loading into the cervical spine as the weight of the head and upward pressure of the flattening thoracic spine serve as end point forces to damage the cervical spine. Where present, the thoracic portion of the above seat serves to prevent the flattening of the thoracic spine by having a kyphotic or concave firm contoured shell that takes the shape of the human thoracic spine and maintains this shape during rear end impact. This form contoured shell precedes the crush zone material which plastically deforms and produces a controlled damping of the forces incurred during a rear end collision.
The lumbar section of the seat will conform to the lumbar spinal curves of the human anatomy. The initial foam that contacts the occupants is combined with the crush zone feature to maximize the energy absorbing feature of this technology.
This firm contoured shell will hold its form on impact from the rear end collision. This contoured shell will then plastically deform the crush zone material. The function of the crush zone, whatever materials are used, is to initiate a controlled damping of forces that result in little or no rebound energy to the occupant.
The crush zone may comprise one or more air bladders, and valve means responsive to rear end vehicular impact to the one or more bladders to at least partially deflate. The inflexible shell can, for example, be linked to one or more mechanical actuators which open the valves upon a predetermined displacement of the shell; or one or more sensors can upon detecting a rear end impact, actuate the valves to enable controlled deflation of the air bladders.
Similarly, one or more rear impact sensors can enable control signals upon an impact of sufficient magnitude, which signal disables a restraint means, e.g. by releasing a mechanical stop which otherwise prevents displacement of the inflexible shell (or of a plate linked to the shell) against or into the crush zone.
In another aspect of the U.S. Pat No. 5,580,124 disclosure, the crush zone can comprise an impact collapsible cellular structure, such as a frangible foam. In still a further aspect, the crush zone may comprise an elastically deformable material which absorbs energy at a substantially more rapid than it releases same.
The crush zone may be sandwiched between the inflexible shell and a spaced fixed, rigid plate; or the crush zone can be spaced from the rear of the shell and contacted and compressed by an intermediate plate which is linked for displacement with the shell. Rearward displacement of the shell may be resisted by restraining means adapted to collapse at a preset strain.